Our research goals continue to be to learn more about the synthesis of collagen and its control. We are continuing our major project of the past 2-3 years, the isolation and characterization of dhe messenger RNA's that code for collagen. One approach has been to isolate the poly A-containing RNA, using an oligo-dT cellulose column, from a polysomal pellet derived from chick embryos. This RNA is then separated into different fractions by sedimentation on a 5-20 percent sucrose gradient and assayed for its ability to direct the synthesis of collagen in a cell-free system derived from mouse Krebs II Ascites cells. Preliminary identifcation of 2 different mRNA fractions as collagen messages has been made. Another approach, which we hope will complement the above, has been the preparation of a specific antibody against chick bone collagen which has been used to precipitate only the collagen polysomes from sucrose gradients. We are currently isolating radioactive, poly A-containing RNA from such pellets in order to determine its size and, if suffciently homogeeous, its base-composition. We also hope to confirm the identity of this RNA as collagen message by its translation in the Krebs ascites cell-free system. The poly-A content and in vivo lifetime of these mRNA's will also be examined.